Bismuth telluride heat pump.
An example of the element Tellurium

Bismuth telluride heat pump.
This is a small bismuth telluride thermoelectric heat pump. Apply a DC voltage and one side gets cold while the other side gets hot. If you attach a good heat sink and fan to the hot side, you can pump heat out of something, cooling it down. This particular device was deployed inside a USB-powered mini-fridge designed to cool one can of soda using power from your computer.Source:eBay seller goods_keeperContributor:Theodore GrayAcquired:28 March, 2009Text Updated:29 March, 2009Price: $6Size: 1.5"Purity: <20%